Transmitting method and transmitter apparatus

ABSTRACT

A transmitting method and a transmitter apparatus, which need no manual adjustment, are disclosed. A delay amount of a delay means is automatically adjusted such that an out-of-band distortion component of a transmission signal is minimized, and a correct timing is produced by the method and the apparatus. In this transmitter apparatus, a first delay means adjusts a control timing over a voltage that controls a power amplifying means, and a distributor distributes an output from the power amplifying means in order to feedback parts of the output. A distortion adjusting means calculates a distortion component of the transmission signal by using the signal fed back by the distributor, and adjusts automatically a delay amount of the first delay means so as to minimize the distortion component. This structure allows eliminating manual adjustment, and obtaining high power-efficiency with fewer distortions.

TECHNICAL FIELD

The present invention relates to a transmitting method and a transmitterapparatus that improve the linearity and the power efficiency of a poweramplifier in a radio communication system.

BACKGROUND ART

A power amplifier of a transmitter apparatus in a radio communicationsystem is a circuit that consumes the largest amount of power in theentire apparatus, thus the power amplifier has been required to improveits power efficiency. Radio communication systems in recent yearstransmit a large amount of data, so that linear modulation signals at ahigh speed and in a broadband are used. Thus a non-linear amplifier ofhigh power-efficiency, such as class C or class D amplifier, is notused. Instead, a liner amplifier of lower power-efficiency, such asclass A or class AB amplifier is used with an appropriate margin inback-off (difference between the max. output amplitude level and thesaturated output power level).

A smaller back-off for improving the power efficiency sometime increasesdistortions and widens spectrum of the transmitter apparatus, therebyinterfering in an adjacent communication channel.

One of the methods to solve the problem of improving the powerefficiency and yet retaining the linearity of a power amplifier is amethod of envelope elimination and restoration (EER). This method isdisclosed in “Single-sideband transmission by envelope elimination andrestoration” written by Kahn, in Proc. IRE, July 1952, page 803-806.According to this method, a transmitter apparatus decomposes atransmission signal into an amplitude component and a phase component,and the phase component, which is to be an envelope signal, is amplifiedby a non-linear amplifier of high power-efficiency. The power supply ofthe amplifier is controlled by the amplitude component. The amplitudecomponent and the phase component are thus restructured.

FIG. 7 shows a structure of a transmitter apparatus adopting the methodof envelope elimination and restoration. Distributor 302 receivestransmission RF signal 301 and distributes it to amplitude limiter 303and envelope detector 306. Limiter 303 limits the amplitude of thesignal distributed by distributor 302 to a bandwidth, thereby obtaininga phase component of transmission RF signal 301. Delay circuit 304appropriately delays an output of limiter 303.

Power amplifier 305 amplifies an output from delay circuit 304 up to adesirable power level. Envelope detector 306 envelope-detects a signalsupplied from distributor 302, thereby obtaining an amplitude componentof transmission RF signal 301. Voltage control DC converter 307 outputsa voltage based on a signal supplied from envelope detector 306.Converter 307 controls power amplifier 305 with this voltage.

For instance, when a field effect transistor (FET) is used as poweramplifier 305, the voltage supplied from converter 307 controls thedrain voltage of power amplifier 305, so that converter 307 modulatesthe amplitude. The operation discussed above restructures the amplitudecomponent and the phase component of the output from power amplifier 305into a signal, which is then transmitted from antenna 308.

A method of envelope tracking is known as another method to solve theproblem of improving the power efficiency and retaining the linearity,this method is disclosed in “Power amplifiers and transmitters for RFand microwave” written by Raab, F. H.; Asbeck, P; Cripps, S; Kenigton,P. B.; Popovic, Z. B.; Pothecary, N.; Sevic, J. F.; Sokal, N. O.;microwave Theory and Techniques, IEEE Transactions on, Volume: 50 Issue:3 Mar. 2002, pages: 814-826.

According to this method, an envelope detector detects an amplitudecomponent of a transmission RF signal, and a voltage to be supplied tothe power amplifier is controlled in response to the amplitude componentdetected. The original transmission RF signal, which includes not only aphase component but also an amplitude component, is supplied to thepower amplifier, which thus needs to be a linear amplifier.

In the conventional structures discussed above, the voltage controltiming needs to be provided exactly to a transmission signal by a delaycircuit. FIG. 8A shows a spectrum of a transmission signal having atiming error in voltage control, and FIG. 8B shows a spectrum where notiming error in voltage control is observed.

A timing error produces distortion components 401 as shown in FIG. 8A,and the distortions degrade the performance of the transmission signalas well as interfere in the adjacent channel. No timing errors producetransmission signal 402 free from distortions as shown in FIG. 8B.However, the timing adjustment discussed above is manually done and is atime-consuming job. The timing once adjusted sometimes cannot follow thechanges caused by temperature changes or aged deterioration incharacteristics of the apparatus.

DISCLOSURE OF THE INVENTION

The present invention aims to provide a transmitting method and atransmitter apparatus which can save manual adjustment, adjustautomatically a delay amount of a delaying means so that a distortioncomponent out-of-band of a transmission signal can be minimized, andproduce a correct timing.

The transmitting method of the present invention controls a voltage of apower amplifying means in response to an envelope amplitude of atransmission signal. To be more specific, the method detects adistortion component of an output signal supplied from the poweramplifying means, and automatically controls a timing of controlling thevoltage that controls the power amplifying means.

The foregoing method eliminates manual adjustment, and adjustsautomatically a delay amount of a delaying means so that a distortioncomponent out-of-band of a transmission signal can be minimized, andproduces a correct timing.

The transmitter apparatus of the present invention comprises thefollowing elements:

-   -   a first delaying means for adjusting a timing of controlling the        voltage that controls the power amplifying means;    -   a distributor for distributing an output from the power        amplifying means to feedback the output; and    -   a distortion adjusting means for calculating a distortion        component of a transmission signal by using a signal fed back by        the distributor, and adjusting automatically a delay amount of        the first delaying means so that the distortion component can be        minimized.

The foregoing structure eliminates the manual adjustment, and adjustsautomatically a delay amount of a delaying means so that a distortioncomponent out-of-band of the transmission signal can be minimized, andproduces a correct timing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram illustrating a transmitter apparatus inaccordance with a first exemplary embodiment of the present invention.

FIG. 2 shows a block diagram illustrating a transmitter apparatus inaccordance with a second exemplary embodiment of the present invention.

FIG. 3 shows a block diagram illustrating a transmitter apparatus inaccordance with a third exemplary embodiment of the present invention.

FIG. 4 shows a block diagram illustrating a transmitter apparatus inaccordance with a fourth exemplary embodiment of the present invention.

FIG. 5 shows a block diagram illustrating a transmitter apparatus inaccordance with a fifth exemplary embodiment of the present invention.

FIG. 6 shows a block diagram illustrating a transmitter apparatus inaccordance with a sixth exemplary embodiment of the present invention.

FIG. 7 shows a block diagram illustrating a conventional transmitterapparatus.

FIG. 8 shows characteristics of spectrum of a transmission signal whentiming errors happen or when no errors happen at the timing ofcontrolling a voltage of a power amplifier.

BEST MODE FOR PRACTICING THE INVENTION

Exemplary embodiments of the present invention are demonstratedhereinafter with reference to the accompanying drawings.

Exemplary Embodiment 1

FIG. 1 shows a block diagram illustrating a transmitter apparatus inaccordance with the first exemplary embodiment of the present invention.Delay circuit 102 delays its input signal before outputting it. DAconverter 103 converts its input signal into an analog signal. Frequencyconverter 104 up-converts its input signal into an RF signal. Poweramplifier 105 amplifies its input signal. Amplitude calculator 106calculates an amplitude component of its input signal before outputtingit.

Delay circuit 107 delays its input signal. DA converter 108 converts itsinput signal into an analog signal. Voltage control DC converter 109outputs a voltage that controls power amplifier 105 based on an outputfrom DA converter 108. Distributor 110 distributes an output from poweramplifier 105 to antenna 111 and frequency converter 112.

Antenna 111 transmits the signal distributed by distributor 110.Frequency converter 112 converts a frequency of the signal distributedby distributor 110. AD converter 113 converts its input signal into adigital signal. Out-of-band power calculator 114 calculates out-of-bandpower of its input signal. Delay amount calculator 115 calculates anamount of delay and outputs it so that the out-of-band power calculatedby calculator 114 can be minimized.

An operation of the foregoing transmitter apparatus is demonstratedhereinafter. Delay circuit 102 delays transmission base-band signal 101by an amount designated by delay amount calculator 115. DA converter 103converts the signal supplied from delay circuit 102 into an analogsignal. Frequency converter 104 up-converts the signal supplied fromconverter 103 into a desirable RF signal. Power amplifier 105 amplifiesthe signal supplied from frequency converter 104 up to a desirable powerlevel.

The input signal to power amplifier 105 is a linear modulation signalaccompanying changes in envelope-amplitude, so that a linear amplifierof class A or class AB is employed.

On the other hand, amplitude calculator 106 calculates an amplitudecomponent of the transmission base-band signal, then outputs it. Delaycircuit 107 delays the amplitude component supplied from calculator 106by an amount designated by delay calculator 115. DA converter 108converts the signal supplied from delay circuit 107 into an analogsignal. Based on the output from DA converter 108, voltage control DCconverter 109 outputs a voltage that controls power amplifier 105. Forinstance, when an FET is used as power amplifier 105, its drain voltageor gate voltage is controlled with a voltage supplied from voltagecontrol DC converter 109.

Distributor 110 distributes the output from power amplifier 105 toantenna 111 and frequency converter 112. Antenna 111 transmits thesignal distributed from distributor 110. Frequency converter 112down-converts the signal distributed from distributor 110 into abase-band signal or an IF signal. AD converter 113 converts the signalsupplied from frequency converter 112 into a digital signal.

Out-of-band power calculator 114 calculates out-of-band power of thesignal supplied from AD converter 113. The out-of-band power is, e.g. anamount of leakage power to an adjacent channel or a leakage power ratioto the adjacent channel. If the leakage power ratio exceeds a givenvalue due to malfunction of power amplifier 105, the operation of theapparatus is stopped, so that transmission of an abnormal signal fromantenna 111 is prevented.

Delay amount calculator 115 calculates a delay amount such that theout-of-band power obtained by calculator 114 can be minimized, andoutputs the resultant amount to delay circuits 102 and 107.

As discussed above, in the transmitter apparatus, delay amountcalculator 115 sets a delay amount in delay circuits 102 and 107 suchthat the out-of-band power obtained by out-of-band power calculator 114can be minimized. A control timing over power amplifier 105 isautomatically adjusted by voltage control DC converter 109. Thus thetransmitter apparatus can obtain high power-efficiency with fewerdistortions.

Delay circuits 102 and 107 can be formed of buffer memories in anecessary and changeable unit of delay or tapped delay lines. An amountof buffer of the memories or a tap coefficient is changed in the case ofchanging a delay amount.

Exemplary Embodiment 2

FIG. 2 shows a block diagram illustrating a transmitter apparatus inaccordance with the second exemplary embodiment of the presentinvention. Computation circuit 218 is formed of amplitude calculator 202and phase calculator 203. Amplitude calculator 202 calculates anamplitude component of transmission base-band signal 201 suppliedthereto. Phase calculator 203 calculates a phase component of signal 201supplied thereto. Delay circuit 204 delays an output signal suppliedfrom phase calculator 203.

DA converter 205 converts the output from delay circuit 204 into ananalog signal. Voltage control oscillator 206 carries out phasemodulation based on the output from DA converter 205. Frequencyconverter 207 converts a frequency of the output from oscillator 206.Power amplifier 208 amplifies the output from frequency converter 207 upto a desirable level. Delay circuit 209 delays the output supplied fromamplitude calculator 202.

DA converter 210 converts the output signal from delay circuit 209 intoan analog signal. Based on the output signal from converter 210, voltagecontrol DC converter 211 outputs a voltage that controls amplifier 208.Distributor 212 distributes the signal supplied from amplifier 208 toantenna 213 and frequency converter 214. Antenna 213 transmits thesignal distributed by distributor 212.

Frequency converter 214 converts a frequency of the signal distributedby distributor 212. AD converter 215 converts a signal supplied fromfrequency converter 214 into a digital signal. Out-of-band powercalculator 216 calculates out-of-band power of a signal suppliedthereto. Delay amount calculator 217 calculates a delay amount such thatthe out-of-band power obtained by calculator 216 is minimized, andoutputs the resultant amount.

An operation of the foregoing transmitter apparatus is demonstratedhereinafter. Computation circuit 218 receives transmission base-bandsignal 201, and calculates an amplitude component at amplitudecalculator 202 as well as calculates a phase component at phasecalculator 203. Delay circuit 204 delays the phase component suppliedfrom phase calculator 203 by an amount designated by delay amountcalculator 217. DA converter 205 converts the signal supplied from delaycircuit 204 into an analog signal.

Voltage control oscillator 206 carries out phase modulation based on thesignal supplied from DA converter 205. Frequency converter 207up-converts the output from oscillator 206 into an RF signal. Poweramplifier 208 amplifies the output from frequency converter 207 up to adesirable level. The signal fed into amplifier 208 is an envelopesignal, so that amplifier 208 can employ a class C or class D non-linearamplifier excellent in power efficiency.

On the other hand, delay circuit 209 delays an amplitude componentsupplied from amplitude calculator 202 by a delay amount designated bydelay amount calculator 217. DA converter 210 converts the signalsupplied from delay circuit 209 into an analog signal. Based on thesignal output from DA converter 210, voltage control DC converter 211outputs a voltage that controls power amplifier 208.

For instance, when an FET is used as amplifier 208, the drain voltage ofamplifier 208 is controlled with the voltage supplied from converter211, thereby carrying out amplitude modulation. Distributor 212distributes an output from amplifier 208 undergone the amplitudemodulation under the control of converter 211 to antenna 213 andfrequency converter 214. Antenna 213 transmits the signal distributed bydistributor 212.

Frequency converter 214 down-converts the signal distributed bydistributor 212 into a base-band signal or an IF signal. AD converter215 converts the signal supplied from frequency converter 214 to adigital signal. Out-of-band power calculator 216 calculates out-of-bandpower of a transmission signal included in the output from AD converter215. The out-of-band power is, e.g. an amount of leakage power to anadjacent channel or a leakage power ratio to the adjacent channel.

If the leakage power ratio exceeds a given value due to malfunction ofpower amplifier 208, the operation of the apparatus is stopped, so thattransmission of an abnormal signal from antenna 213 is prevented. Basedon an output from out-of-band power calculator, delay amount calculator217 calculates a delay amount such that the out-of-band power obtainedby calculator 216 becomes minimized, and outputs the resultant amount todelay circuits 204 and 209.

As discussed above, in the transmitter apparatus, delay amountcalculator 217 sets a delay amount in delay circuits 204 and 209 suchthat the out-of-band power obtained by out-of-band power calculator 216is minimized. A control-timing over power amplifier 208 is automaticallyadjusted by voltage control DC converter 211. Thus the apparatus canobtain high power-efficiency with fewer distortions.

Exemplary Embodiment 3

FIG. 3 shows a block diagram illustrating a transmitter apparatus inaccordance with the third exemplary embodiment of the present invention.Computation circuit 518 is formed of amplitude calculator 502 and phasecalculator 503. Amplitude calculator 502 calculates an amplitudecomponent of transmission base-band signal 501 supplied thereto. Phasecalculator 503 calculates a phase component of signal 501 suppliedthereto. Delay circuit 504 delays an output signal supplied from phasecalculator 503.

DA converter 505 converts the output from delay circuit 504 into ananalog signal. Voltage control oscillator 506 carries out phasemodulation based on the output from DA converter 505. Frequencyconverter 507 converts a frequency of the output from oscillator 506.Power amplifier 508 amplifies the output from frequency converter 507 upto a desirable level. Delay circuit 509 delays the output supplied fromamplitude calculator 502.

DA converter 510 converts the output signal from delay circuit 509 intoan analog signal. Based on the output signal from converter 510, voltagecontrol DC converter 511 outputs a voltage that controls amplifier 508.Distributor 512 distributes the signal supplied from amplifier 508 toantenna 513 and frequency converter 514. Antenna 513 transmits thesignal distributed by distributor 512.

Frequency converter 514 converts a frequency of the signal distributedby distributor 512. AD converter 515 converts a signal supplied fromfrequency converter 514 into a digital signal. Error componentcalculator 516 calculates an error component between an output signalfrom AD converter 515 and transmission base-band signal 501. Delayamount calculator 517 calculates a delay amount such that the errorcomponent obtained by calculator 516 becomes minimized, and outputs theresultant amount.

The transmitter apparatus in accordance with the third embodiment has astructure where delay amount calculator 517 calculates a delay amountbased on the calculation done by error component calculator 516. Thusthe same operations as those in the second embodiment are omitted here,and the different operations are focused hereinafter.

The processes starting from the calculation of the amplitude componentand the phase component of transmission base-band signal 501 bycomputation circuit 518 to the transmission of the signal from antenna513 via distributor 512 by power amplifier 508 are the same as those ofthe second embodiment.

Frequency converter 514 down-converts the signal distributed bydistributor 512 into a base-band signal. AD converter 515 converts thesignal supplied from frequency converter 514 to a digital signal. Errorcomponent calculator 516 receives the output signal from AD converter515 and transmission base-band signal 501, and calculates an errorcomponent between those two signals at every sampling timepredetermined.

Based on the error component supplied from calculator 516, delay amountcalculator 517 calculates a delay amount such that the error componentbecomes minimized, and outputs the resultant amount to delay circuit 502and 509.

As discussed above, in the transmitter apparatus, delay amountcalculator 517 sets a delay amount in delay circuits 504 and 509 suchthat the error component obtained by error component calculator isminimized. A control timing over power amplifier 508 is automaticallyadjusted by voltage control DC converter 511. Thus the transmitterapparatus can obtain high power-efficiency with fewer distortions.

Exemplary Embodiment 4

FIG. 4 shows a block diagram illustrating a transmitter apparatus inaccordance with the fourth exemplary embodiment of the presentinvention. Computation circuit 602 is formed of amplitude calculator 615and phase calculator 616. Amplitude calculator 615 calculates anamplitude component of transmission base-band signal 601 suppliedthereto. Phase calculator 616 calculates a phase component of signal 601supplied thereto. DA converter 603 converts the output from phasecalculator 616 into an analog signal.

Filter 604 passes specific frequencies out of a signal output from DAconverter 603. Delay circuit 605 delays a signal output from filter 604.Phase modulator 606 carries out phase modulation based on a signaloutput from delay circuit 605. Power amplifier 607 amplifies an outputfrom phase modulator 606 up to a desirable power level. DA converter 608converts a signal output from amplitude calculator 615 into an analogsignal.

Filter 609 passes specific frequencies out of a signal output from DAconverter 608. Delay circuit 610 delays a signal output from filter 609.Based on a signal output from delay circuit 610, amplitude modulator 611outputs a voltage that controls power amplifier 607. Distributor 612distributes a signal supplied from power amplifier 607 to antenna 613and distortion detector 614.

Antenna 613 transmits the signal distributed by distributor 612.Distortion detector 614 detects a distortion of the signal distributedby distributor 612, and sets a delay amount of delay circuits 605 and610.

An operation of the foregoing transmitter apparatus is demonstratedhereinafter. Computation circuit 602 receives transmission base-bandsignal 601, and calculates an amplitude component at amplitudecalculator 615 as well as calculates a phase component at phasecalculator 616. DA converter 603 converts the phase component suppliedfrom calculator 616 into an analog signal. Filter 604 passes specificfrequencies out of the output from DA converter 603 and eliminatesunnecessary frequencies.

Delay circuit 605 delays a signal supplied from filter 604 by an amountset by distortion detector 614. Phase modulator 606 carries out phasemodulation based on a signal output from delay circuit 605. Poweramplifier 607 amplifies an output from phase modulator 606 up to adesirable power level.

On the other hand, DA converter 608 converts the amplitude componentoutput from amplitude calculator 615 to an analog signal. Filter 609passes a specific frequency out of an output from DA converter 608, andeliminates unnecessary frequencies. Delay circuit 610 delays a signaloutput from filter 609 by an amount set by distortion detector 614.

Based on a signal output from delay circuit 610, amplitude modulator 611outputs a voltage that controls power amplifier 607. This controlvoltage is applied to power amplifier 607 to output an amplitudecomponent.

Phase modulator 606 is, e.g. the voltage control oscillator or thefrequency converter used in the previous embodiments 1-3.Amplitude-modulator 611 is, e.g. the voltage control DC converter usedin the previous embodiments 1-3.

Distributor 612 distributes an output from power amplifier 607 toantenna 613 and distortion detector 614. Antenna 613 transmits thesignal distributed by distributor 612.

Distortion detector 614 detects an amount of distortion of the signaldistributed by distributor 612. This detection is carried out by thefollowing method: A transmission signal demodulated is digitallyprocessed by, e.g. Fourier transform, then a level of distortionfrequency component is calculated, or a transmission signal isfrequency-converted into an analog base-band signal, then a distortioncomponent is filtered out for level detection. Delay circuits 605 and610 changes a delay amount with a control signal output from distortiondetector 614.

Distortion detector 614 sets a delay amount such that a distortion to bedetected is minimized. This delay amount is set by the following method:(1) Change a delay amount in an appropriate range for collecting dataabout the relation between delay amounts and distortion amounts, thenselect a delay amount, which gives the minimum distortion, from the datacollected. Or (2) change a delay amount sequentially along measuring adistortion, thereby searching for a point that minimizes the distortionamount.

This transmitter apparatus, which includes a delay circuit in both theroutes of the amplitude component and the phase component, isdemonstrated hereinbefore; however, when which route has a greater delayamount is known in advance, the delay circuit can be disposed in eitherone of the routes.

The transmitter apparatus, which includes delay circuits 605 and 610coupled to a stage after filters 604 and 609, is demonstratedhereinbefore; however, the function of delay circuits 605 and 610 can beembodied in filters 604 and 609.

Filters 604 and 609 work as low pass filters that smoothen the outputsfrom DA converters 603 and 608. A change in a value of the elementsforming a circuit of the low pass filter thus allows changing a delayamount of a signal within a pass-band.

As discussed above, the transmitter apparatus can reduce the distortionsproduced in the power amplifier, and yet, obtain high power-efficiencyby controlling a delay amount of an amplitude component or a phasecomponent of a transmission signal such that a distortion amount of atransmission output is minimized.

Exemplary Embodiment 5

FIG. 5 shows a block diagram illustrating a transmitter apparatus inaccordance with the fifth exemplary embodiment of the present invention.Computation circuit 704 is formed of amplitude calculator 719 and phasecalculator 720. Amplitude calculator 719 calculates an amplitudecomponent of transmission base-band signal 701 supplied thereto. Phasecalculator 720 calculates a phase component of signal 701 suppliedthereto. Switch 702 is formed of switches 702A and 702B interlockingwith each other.

Switch 702A switches an output from amplitude calculator 719 to/from asignal output from chirp signal source 703, of which frequency isvariable time-dependently, before outputting. Switch 702B switches anoutput from phase calculator 720 to/from a signal output from chirpsignal source 703 before outputting. DA converter 705 converts an outputfrom switch 702B into an analog signal. Filter 706 passes specificfrequencies out of a signal output from DA converter 705.

Delay circuit 707 delays a signal output from filter 706. Carrier signalsource 709 outputs a carrier signal having a constant frequency. Phasemodulator 708 mixes an output from delay circuit 707 and a signal outputfrom carrier signal source 709, thereby producing a phase modulationsignal. Power amplifier 710 amplifies an output from phase modulator 708up to a desirable power level. DA converter 711 converts a signal outputfrom switch 702A into an analog signal.

Filter 712 passes specific frequencies out of a signal output from DAconverter 711. Delay circuit 713 delays a signal output from filter 712.Based on a signal output from delay circuit 713, amplitude modulator 714outputs a voltage that controls power amplifier 710. Distributor 715distributes a signal from power amplifier 710 to antenna 716 andfrequency converter 717.

Antenna 716 transmits the signal distributed from distributor 715.Frequency converter 717 converts a frequency of the signal distributedfrom distributor 715 by using the signal output from carrier signalsource 709. Frequency component detector 718 controls a delay amount ofdelay circuits 707 and 713 based on a signal output from frequencyconverter 717.

An operation of the foregoing transmitter apparatus is demonstratedhereinafter. In this transmitter apparatus, when a delay amount of delaycircuits 707 and 713 is adjusted, input signals to DA converters 705 and711 are switched from an output signal of computation circuit 702 to anoutput signal of chirp signal source 703 with switch 702. The chirpsignal fed into DA converter 705 runs as a first chirp signal fromswitch 702B through DA converter 705, filter 706 and arrives at delaycircuit 707.

Phase modulator 708 mixes the first chirp signal supplied from delaycircuit 707 with the carrier signal output from carrier signal source709. Power amplifier 710 amplifies an output from phase modulator 708 upto a desirable power level.

On the other hand, a chirp signal fed into DA converter 711 runs as asecond chirp signal from switch 702A through DA converter 711, filter712 and arrives at delay circuit 713. Amplitude modifier 714 controls abias voltage of power amplifier 710 with the second chirp signalsupplied from delay circuit 713. As a result, power amplifier 710outputs a signal formed by mixing the first chirp signal with the secondchirp signal.

The signal output from power amplifier 710 is distributed throughdistributor 715, and parts of the signal are fed into frequencyconverter 717, which then mixes the signal from distributor 715 with thecarrier signal from carrier signal source 709, thereby obtaining asignal having a frequency component which is a difference between thefirst chirp signal and the second chirp signal.

The first and second chirp signals are mixed in power amplifier 710, andwhen no delay exists between the route of the amplitude component andthe route of the phase component, the signals having the same frequencyare mixed. Thus frequency converter 717 outputs a signal having a dccomponent only. On the other hand, when some delay exists between theforegoing two routes, frequency converter 717 outputs a signal having anac component.

Frequency component detector 718 detects the ac component, i.e.frequency component, from the output signal of frequency converter 717,and adjusts the delay amount of delay circuits 707 and 713 such that thefrequency component has only a dc component, thereby controlling thetiming between both the routes. An output from frequency converter 717includes a frequency component that is a sum of the first and secondchirp signals; however, this component is not needed, so that it issuppressed by the low pass filter.

As discussed above, the transmitter apparatus uses chirp signals insteadof a transmission base-band signal, thereby detecting a frequencycomponent of a signal down-converted from an output of the poweramplifier. A delay amount of the delay circuits is so adjusted as thefrequency component has only a dc component, so that the timings of theroute of amplitude component and the route of phase component can agreewith each other. As a result, the transmitter apparatus, in which thedistortions produced in the power amplifier can be reduced and yet highpower-efficiency is realized, is obtainable.

Exemplary Embodiment 6

FIG. 6 shows a block diagram illustrating a transmitter apparatus inaccordance with the sixth exemplary embodiment. Computation circuit 804is formed of amplitude calculator 821 and phase calculator 822.Amplitude calculator 821 calculates an amplitude component oftransmission base-band signal 801 supplied thereto. Phase calculator 822calculates a phase component of signal 801 supplied thereto.

Chirp signal converter 820 converts a signal output from chirp signalsource 803 with a signal from fixed-frequency signal source 805 freefrom time-dependent changes in frequency, then outputs the resultantsignal. Switch 802 is formed of switches 802A and 802B interlocking witheach other.

Switch 802A switches an output from amplitude calculator 821 to/from asignal output from chirp signal source 803 before outputting. Switch802B switches an output from phase calculator 822 to/from a signaloutput from chirp signal source 820 before outputting. DA converter 806converts an output from switch 802B into an analog signal. Filter 807passes specific frequencies out of a signal output from DA converter806. Carrier signal source 809 outputs a carrier signal having aconstant frequency.

Phase modulator 808 mixes an output from filter 807 and a signal outputfrom carrier signal source 809, thereby producing a phase modulationsignal. Power amplifier 810 amplifies an output from phase modulator 808up to a desirable power level. DA converter 811 converts a signal outputfrom switch 802A into an analog signal. Filter 812 passes specificfrequencies out of a signal output from DA converter 811.

Delay circuit 813 delays a signal output from filter 812. Based on asignal output from delay circuit 813, amplitude modulator 814 outputs avoltage that controls power amplifier 810. Distributor 815 distributes asignal from power amplifier 810 to antenna 816 and frequency converter817. Antenna 816 transmits the signal distributed from distributor 815.

Frequency converter 817 converts a frequency of the signal distributedfrom distributor 815 by using a signal output from carrier signal source809. Phase comparator 818 compares a phase of a signal output fromfrequency converter 817 with a phase of fixed-frequency signal source805. Control signal filter 819 controls phase-lock between phasecomparator 818 and delay circuit 813.

An operation of the foregoing transmitter apparatus is demonstratedhereinafter. This transmitter apparatus operates basically in the samemanner as that of the fifth embodiment. This apparatus uses thefollowing two signals: a first chirp signal generated by chirp signalsource 803; a second chirp signal output from chirp signal converter 820which mixes fixed-frequency signal source 805 with the first chirpsignal for outputting the second chirp signal.

The first chirp signal is output from DA converter 811 to a signal routeof the amplitude component, and the second chirp signal is output fromDA converter 806 to a signal route of the phase component. If there isno delay between those two routes, and if those two signals are mixed atthe same timing in power amplifier 810, frequency converter 817 outputsa signal having the same frequency as that of fixed-frequency signalsource 805.

The signal having the same frequency as that of fixed-frequency signalsource 805 is that the frequency of the signal is equal to a differencein frequency between the first and second chirp signals. Therefore,phase comparator 818 compares the phase of a signal output fromfrequency converter 817 with the phase of a signal output fromfixed-frequency signal source 805. Then comparator 818 adjusts a delayamount of delay circuit 813 such that the difference in phase becomesconstant, i.e. the frequencies become equal to each other, therebycontrolling the timing between both of the routes.

Delay circuit 813 is formed of circuit elements of which values arechanged by a voltage of, e.g. varactor diode, so that a delay amount canbe controlled by a voltage. At the same time, control signal filter 819is disposed as a loop filter, so that phase-lock operation between phasecomparator 818 and delay circuit 813 can be controlled. Thosepreparations allow the phase-lock control to adjust the timing of mixingthe amplitude component with the phase component in power amplifier 810.

A frequency difference between the first and second chirp signals outputfrom frequency converter 817 happens to agree with the frequency offixed-frequency signal source 805. However, this phenomenon can beavoided by setting the changes in frequency of the chirp signalsappropriately in response to a presumable difference in delay betweenthe signal routes.

The transmitter apparatus having delay circuit 813 in the route ofamplitude component is discussed above; however, if a signal runs fasterin the route of phase component than in the route of amplitudecomponent, the delay circuit is disposed in the route of phasecomponent.

The transmitter apparatus thus uses two chirp signals, of whichfrequency difference is constant, instead of a transmission modulationsignal. A delay amount of the delay circuit is controlled such that asignal down-converted from an output of the power amplifier by a carrierfrequency signal becomes the same as the signal of fixed frequencysource 905, i.e. the signal of the frequency difference between thefirst and the second chirp signals. This control achieves the phaselock. Those preparations allow the amplitude component and the phasecomponent to be mixed automatically at the same timing in the poweramplifier, so that the power amplifier can reduce its distortions andobtain high power-efficiency.

Industrial Applicability

The transmitter apparatus of the present invention can detect adistortion component of a signal output from a power amplifying means,and control a timing of a voltage which automatically controls the poweramplifying means to minimize the distortion component. This structureallows reducing distortions of a transmission signal as well asimproving power efficiency of the power amplifying means.

1. A transmitting method that controls a voltage of a power amplifyingmeans in response to an envelope amplitude of a transmission signal, themethod comprising: detecting a distortion component of a signal outputfrom the power amplifying means, and controlling automatically a controltiming over a voltage that controls the power amplifying means such thatthe distortion component is minimized.
 2. The transmitting method ofclaim 1, wherein the distortion component is out-of-band power of thetransmission signal.
 3. A transmitter apparatus comprising: a firstdelay means for adjusting a control timing over a voltage that controlsa power amplifying means; a distributor for distributing an output fromthe power amplifying means and feeding back a signal distributed; and adistortion adjusting means for calculating a distortion component of atransmission signal by using the signal fed back by the distributor, andadjusting automatically a delay amount of the first delaying means suchthat the distortion component is minimized.
 4. The transmitter apparatusof claim 3, wherein the distortion component is out-of-band power of thetransmission signal.
 5. The transmitter apparatus of claim 4 furthercomprising: an amplitude calculating means for calculating an amplitudeof a transmission base-band signal; a voltage controlling means forcontrolling a bias voltage to be supplied to the power amplifying meansbased on an output from the first delay means; a second delay means fordelaying the transmission base-band signal; a first frequency convertingmeans for converting an output from the second delay means into an RFsignal; a second frequency converting means for converting the signalfed back into one of a base-band signal and an IF signal; and a delayamount calculating means for adjusting a delay amount supplied by thefirst delay means and the second delay means based on an output from thedistortion adjusting means such that the out-of-band power calculated bythe distortion adjusting means becomes minimized, wherein the firstdelay means delays an output from the amplitude calculating means, thevoltage controlling means controls the bias voltage based on the outputfrom the first delay means, the power amplifying means amplifies anoutput from the first frequency converting means, and the distortionadjusting means calculates the out-of-band power based on an output fromthe second frequency converting means.
 6. The transmitter apparatus ofclaim 5, wherein the out-of-band power is leakage power to an adjacentchannel.
 7. The transmitter apparatus of claim 6, wherein an abnormaloutput from the distortion adjusting means halts an operation of thetransmitter apparatus.
 8. The transmitter apparatus of claim 5, whereinan abnormal output from the distortion adjusting means halts anoperation of the transmitter apparatus.
 9. The transmitter apparatus ofclaim 5 further comprising: a phase calculating means for calculating aphase of the transmission base-band signal; and a voltage controloscillating means for outputting a phase modulation signal based on theoutput from the second delay means, wherein the second delay meansdelays an output from the phase calculating means, and the firstfrequency converting means converts an output from the voltage controloscillating means into an RF signal.
 10. The transmitter apparatus ofclaim 9, wherein the out-of-band power is leakage power to an adjacentchannel.
 11. The transmitter apparatus of claim 10, wherein an abnormaloutput from the distortion adjusting means halts an operation of thetransmitter apparatus.
 12. The transmitter apparatus of claim 9, whereinan abnormal output from the distortion adjusting means halts anoperation of the transmitter apparatus.
 13. The transmitter apparatus ofclaim 3 further comprising: a voltage control oscillating means forproducing a carrier signal having a constant envelope and beingphase-modulated by a phase component of a transmission base-band signal;and a third delay means for delaying a signal of the phase component tobe fed into the voltage control oscillating means, wherein thedistortion adjusting means adjusts not only a delay amount of the firstdelay means but also a delay amount of the third delay means.
 14. Thetransmitter apparatus of claim 13, wherein the third delay means is afirst filter that limits a signal of the phase component to a band, thefirst delay means is a second filter that limits a signal of theamplitude component to a band, the distortion adjusting means changespassing characteristics of one of the first filter and the second filterfor controlling a delay amount.